Lowrance AirMap 300 GPS: So What's New?

In January 1998, Lowrance Avionics introduced an improved model of their AirMap handheld GPS. The AirMap 300 is identical in size, shape and function to its predecessor, but uses a 12-channel Rockwell GPS “engine” instead of the 5-channel chip used in previous AirMaps. We took both new and old AirMap units flying (plus a Garmin GPSMAP-195 as a benchmark) and here is our detailed evaluation ... plus lots of photos.

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About the Author ...

Mike Busch is editor-in-chief of
AVweb, a member of the technical staff at Cessna Pilots Association, and in a
prior lifetime was a contributing editor for The Aviation Consumer and IFR
Magazine. A 6,000-hour commercial pilot and CFI with airplane, instrument and
multiengine ratings, Mike has been flying for 36 years and an aircraft owner
for 33. For the past 14 of those years, he's owned and flown a Cessna T310R
turbocharged twin, which he maintains himself. In his never-ending quest to
become a true renaissance man of aviation, Mike's on the verge of earning his
A&P mechanic certificate. Mike and his wife Jan reside on the central
coast of California in a semi-rural area where he can't get DSL or cable
TV.

Let me state right up front that I've been a big fan of
the Lowrance AirMap since its introduction in 1996. I wouldn't rate it as the best
handheld aviation GPS on the market...I'd have to award that distinction to the Garmin
GPSMAP-195. But the AirMap is a very close runner-up to the Garmin and costs a lot less
(like $400 to $500 less), making it easily the "best bang for the buck" among
all aviation handhelds.

As an AirMap fan, I started getting worried a few months ago when I started hearing
rumors from various dealers that Lowrance was about to discontinue the AirMap and
introduce a new model to replace it. The rumor mill said that the new Lowrance would be a
much smaller unit, similar in size to the diminutive Garmin GPS III Pilot, and would sport
a new 12-channel GPS receiver (like the Garmins) instead of the 5-channel engine in the
AirMap. This concerned me because I don't care for the little Garmin III at all — I find
its display and especially its keypad much too small for cockpit use — and didn't want to
see Lowrance follow in those footsteps. It was also rumored that the new Lowrance unit was
an all-new clean-sheet design, and that its software was plagued with glitches (much like
the AirMap's was when it first appeared on the market). It sounded to me as if Lowrance
was about to shoot itself in the foot.

I needn't have worried. As so often happens, the rumor mill was wrong.

Evolution, not revolution (thank heavens)

Lowrance's new
aviation handheld is called the "AirMap 300" and, very simply, it's almost
identical to its predecessor except that it uses a new Rockwell GPS engine with 12
parallel channels instead of the 5-channel Rockwell chip set used in the original AirMap.
But that's the only thing that the rumor mill got right. Other than the new 12-channel
receiver, not much has changed at all.

In fact, it's hard to tell the newer and older models apart just by looking at them.
The biggest physical difference is in the keypad, where the keys have changed from white
(AirMap) to black (AirMap 300). The flip-top antenna is marked "AIRMAP 300" and
"12-Channel Receiver." That's about it.

My AirMap is a very early unit, so I also noticed a
number of other incremental improvements that Lowrance has made to the product since I
bought mine. The original awkward-to-remove thumbwheel-type antenna was replaced by a
much-improved quick-release antenna. The cigarette lighter power cord was redesigned to
make more reliable contact. The operating software has been upgraded many times in the
past two years, correcting bugs, improving the user interface, and adding numerous useful
features such as vertical navigation, runway centerline extensions, moveable present
position and map center, and map depiction of obstructions. And the owner's manual has
been rewritten and much improved. But none of these hardware and software improvements are
unique to the AirMap 300, and all are available to owners of older AirMaps like mine.

When I first got my hands on the AirMap 300, I quickly
explored the various screens and menus to see what software changes had been made. The
only change I could find was the one I expected: the "Satellite Info" screen was
redesigned to make room for 12 channels worth of satellite information (instead of just
5), and the graphic satellite position display and fix quality statistics were moved to a
new screen. Except for that, I was unable to find any differences between the AirMap 300
software and the latest software update for the 5-channel AirMap.

Nor could I find any "bugs" in the AirMap 300 software. Its performance was
solid as a rock, both in my ground testing and in the air.

Flying testbed

Of course, the proof of any aviation GPS is in the
flying, so I decided to do a side-by-side in-flight test of the new 12-channel AirMap 300
with its 5-channel predecessor. I set up my Cessna T310R with dual yoke-mounted
AirMaps...the new AirMap 300 on the left yoke and my venerable 5-channel AirMap on the
right. Both were set up with their antennas detached and suction-cup mounted to the top
corners of the windshield in as symmetrical a fashion as I could manage.

While setting up the airplane, I was reminded of one of my few
remaining gripes with the AirMap: its yoke mount. The mount is well-made and very sturdy,
but it relies on Velcro to attach the receiver to the mount. Unfortunately, the AirMap is
too big and heavy for the Velcro to hold it securely, at least when the battery pack is
attached. In my opinion, the mount really needs some kind of mechanical clamp to hold the
receiver...or else twice as much Velcro surface area. This is one change I would have
liked to see made with the introduction of the AirMap 300, but it wasn't. Oh well.

Yoke mounting works a lot better if the unit is
powered from the airplane's electrical system and the battery pack is not attached to the
bottom of the receiver. The AirMap-minus-battery makes a lightweight, compact package that
fits just perfectly on the yoke, and is held quite snugly by the Velcro mount. I purchased
an extra DC power cord from Lowrance, snipped off the cigarette lighter plug, and wired it
permanently into the electrical system of my airplane. With this reliable source of power,
I generally run the AirMap sans battery, and find it makes a very nice setup.

I invited my friend Chris along to fly right seat and monitor the 5-channel GPS while I
monitored the 12-channel unit. Chris brought along his Garmin GPSMAP-195 and held it on
his lap, with the remote-mount antenna in the center of the windshield. The Garmin also
has a 12-channel receiver and has until now set the standard of excellence in handheld GPS
receiver performance, so we thought it would make a good benchmark with which to compare
the two Lowrance units.

With two experienced pilots and three ground-mapping GPS receivers aboard (not to
mention a panel full of radios), we decided we didn't have any excuse for getting lost!

Timing and torture tests

After starting engines but before taxiing out, Chris
and I ran some preliminary comparison tests of the three GPS receivers. To begin with, we
powered them up exactly simultaneously and timed how long they took to acquire a fix from
a cold start. The AirMap 300 and Garmin -195 repeatedly acquired a position fix in less
than 15 seconds, while the older 5-channel AirMap typically took 25 seconds to lock on.
While this was interesting, it's not clear that it was significant, because I can't recall
ever managing to to complete a taxi-out and runup in less than 25 seconds.

We also tried simulating a loss-of-signal situation by disconnecting the antenna cable
from the two AirMaps, then reconnecting them simultaneously and seeing how long it took
for the receivers to reacquire position. The AirMap 300 consistently did so in 5 seconds
or so, while the older AirMap took up to twice as long. Again, interesting but not
necessarily relevant to actual in-flight performance.

Flight testing frustratingly inconclusive

We proceeded to make a two-hour test flight from my home base of
Santa Maria, Calif., to Watsonville and return. The SMX-WVI leg was made in daylight
conditions, VFR at very low altitude mostly 600' MSL overwater, hugging the picturesque
central California coastline with the cliffs of Big Sur towering above us at three o'clock
(and obscuring satnav reception in that direction). The return flight was night IFR at
9,000' in clouds, light rain and brief rime icing conditions. We even tried some
steep-banked low-level maneuvering. But much to our chagrin, all three GPS receivers
performed flawlessly and never lost position lock during the entire test flight.

We did have the opportunity to evaluate all three ground-mapping displays in a wide
variety of lighting conditions, including extensive use of the backlighting on the night
return flight. Chris and I agreed that the Garmin GPSMAP-195 display is somewhat easier to
read under difficult lighting conditions, partly because the Garmin's display is
half-again as large as the AirMap's, and partly because Garmin's mapping software depicts
features in bolder strokes and larger text. Kudos to Garmin's graphics programmers for a
superb job.

But the primary objective of the test flight was to compare the 5- and 12-channel GPS
engines, to try to get the 5-channel unit to lose lock in-flight, and to see if the
12-channel units would do better. So it was somewhat frustrating that none of the three
receivers hiccuped even once.

Every indication is that the 12-channel Rockwell engine in the AirMap 300 is every bit
as good as the 12-channel receiver in the Garmin -195. At one point during the return
flight from Watsonville, Chris and I compared the satellite info displays of the two
12-channel receivers. The Garmin was tracking 8 satellites simultaneously, using a
windshield-mounted antenna. The AirMap 300 was tracking 9.

So...are 12 channels really better than 5?

Actually, yes. Although the 5-channel AirMap performed perfectly during our controlled
test flight, I've had it lose position in-flight at least a dozen times in the course of
nearly two years and 20,000 NM of flying with the unit. In my experience, the problem
occurs mostly during turns, often while maneuvering for landing or to intercept an
instrument final approach course. This makes a lot of sense if you think about it.

If I were using an externally-mounted GPS antenna, 5
channels would probably be plenty. After all, only 4 satellites need to be tracked for the
receiver to calculate a 3D position fix. In fact, the receiver can continue to track
position with only 3 satellites in view...it does this by assuming the aircraft's altitude
hasn't changed and computing a 2D fix. So a 5-channel receiver can track all the
satellites necessary for a 3D fix, plus a "spare" to provide uninterrupted
navigation when a satellite disappears below the horizon (or in a turn).

But using an inside antenna suction-cupped to the windshield (as I have been doing) or
lying on the glareshield (even worse) is a different story. A windshield-mounted antenna
has its view partially masked by the cabin roof (at least in an aluminum spam can like my
airplane), preventing it from "seeing" satellites located aft of the aircraft.
This usually isn't a problem, because there are still usually plenty of satellites visible
to the front and sides of the aircraft. After all, we only need to see four, and can make
do with just three in a pinch.

But suppose we make a 90-degree turn to the right. After we roll out of the turn, the
GPS can probably still "see" enough satellites to calculate a fix. But here's
the rub: they probably are not the same satellites as the ones the receiver was tracking
before the turn! In other words, several of the satellites that were being tracked prior
to the turn may drop out of sight, and several new satellites may come into view after the
turn. Since it can take 15 to 30 seconds for a receiver to start tracking a new satellite,
it becomes quite possible that the receiver will lose lock briefly before it starts
tracking enough satellites to reestablish a good position fix.

The bottom line is that if you use a good external antenna, almost any GPS receiver
will do a fine job. If you use an inside antenna whose view of the sky is partially
blocked by the airplane's structure, the extra channels will provide a noticeable extra
margin of performance, particularly during maneuvering flight. This may be particularly
important to renter-pilots for whom an external GPS antenna is often not an option.

AirMap 300 Pricing and Packaging

Lowrance has been extremely aggressive with its
pricing of the AirMap. When first introduced in spring of 1996, the price was $899, and
was considered a spectacular bargain at the time. A year later, they introduced a
"Special Edition" model equipped with the rechargeable NiMH pack and priced at
$999. Since then, Lowrance has dropped the price twice, ending up at $599 for the basic
5-channel AirMap and about $100 extra for the NiMH battery.

With the introduction of the 12-channel AirMap 300, Lowrance has done something a bit
unusual: they've included both the alkaline and NiMH batteries with the AirMap 300
as standard equipment, and priced the package at $799. This works out to be an effective
$100 price increase for the 12-channel model over the 5-channel one, since the bundled
NiMH battery used to be a $100 extra-cost option with the 5-channel AirMap.

Even at the higher price, the AirMap 300 remains far-and-away the best
price/performance value in the handheld aviation GPS market. The Garmin GPSMAP-195 is
arguably better in some respects (larger display, better mapping software, better yoke
mount), but it costs half again as much as the AirMap 300.

Lowrance says it will start shipping the AirMap 300 in quantity in late January, and
will no longer manufacture the 5-channel AirMap. There may be a short period of time
during which some dealers may be offering both units (although most dealers I spoke with
are already sold out of the older AirMap). But certainly by mid-February, the only kind of
AirMap you'll be able to buy will be the 12-channel model.

Oh, by the way, did I mention that I like the AirMap 300?

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